WRT54GC not working properly with internet

Yesterday I bought the WRT54GC and set it up. My PC, and a wireless connection, can connect to the router sucessfully, but niether can access the internet. I have a DSL connection that uses DHCP and all the settings seem right. The internet works when directly connected to the computer, so I know that something between the router and the modem (Westell 2200) isn't working. The routers firmware it up-tp-date and everything. I have already turned off and on the modem, router, and PC in the order you are supposed to.